如何将一个类中变量的值用于另一个类？

Question

我在classAccount中定义了一个变量draw。它可以很好地执行Account类中定义的提款功能。但是，我希望访问Sav\u acct类中存在的函数interest中的变量值。它将收回的值取为0。如何使用兴趣函数中的函数中的函数的值，以便执行正确的数学运算？

导入java。util。扫描仪；

类别帐户{

String customer_name;
int account_number;
String type_account;
int balance=2500;
double deposit;

双重撤回；

          void deposit(){
              Scanner sc=new Scanner(System.in);
              System.out.println("how much do you want to deposit?");
              int amo=sc.nextInt();
 deposit= balance+amo;
 
 System.out.println("Your current balance is "+ deposit);

}

作废取款（）{

扫描仪sc=新扫描仪（系统英寸）；

系统出来println（“您想提取多少？”）；

int amo=sc.nextInt（）；

    withdraw=balance-amo;
               
            

}

}

类Curr\u acct扩展帐户{

空语句

void penalty(){
  
     
       
   
       if(withdraw<2000&& withdraw>0){
      double Service_charge=withdraw-100;
       double falling= Service_charge;
     System.out.println("Your balance is "+withdraw);
       System.out.println("You've been charged a service charge"+" 100" +" due to a below the limit balance");
       System.out.println("Your current amount is "+ falling);
   }
       else if(withdraw<=0){
           System.out.println("Your balance is insufficient");
       }
       else{
           System.out.println("Your current balance is "+ withdraw);
       }
  

}

}

class Sav_acct extends Account{
    
        void interest(){
            if(withdraw<0){
                  System.out.println("Your balance is insufficient");
              }
            else{
            double interests;
          
  interests=(1/100)*withdraw;
  double total_amount=interests+withdraw;
  System.out.println("Your new balance with interest is "+total_amount);
            }

}

}

公共类发布{

空语句

公共静态void main（字符串[]参数）{

扫描仪sc=新扫描仪（系统英寸）；

系统出来println（“输入您的姓名”）；

    String n=sc.nextLine();
    
    System.out.println("Enter your account type: Savings Account or Current Account");
    String t=sc.nextLine();
    
    if("Savings Account".equals(t)){
        Sav_acct ac =new Sav_acct();
        System.out.println("Do you want to deposit or withdraw amount?");
        String d=sc.nextLine();
        if("deposit".equals(d)){
            
            
            ac.deposit();
        }
        else if("withdraw".equals(d)){
            
            
            ac.withdrawl();
            
            ac.interest();
                    
                    }
        }

   
    else if("Current Account".equals(t)){
         Curr_acct ac =new Curr_acct();
        System.out.println("Do you want to deposit or withdraw amount?");
        String d=sc.nextLine();
        if("deposit".equals(d)){
            
           
            ac.deposit();
        }
        else if("withdraw".equals(d)){
            
            
            ac.withdrawl();
            
           
                   
                    ac.penalty();
                 
        
           
        }
    }
    else{
        
        System.out.println("please enter the correct account type as per the options provided on the screen");
        
    }
    
   
    
}
}

Answer 1

不要在变量中使用public static来访问它。使用getter访问类的变量。这是正确的做法。

在您的情况下，删除公共静态会很好；在帐户类中

public static double withdraw; 

to 

double withdraw;

在为帐户和Sav_acct类创建对象时，您不会维护任何状态。您正在创建两个不同的对象来完成一项工作。您永远不会在Sav_acct中获取帐户的撤回值，因为两者都是不同的对象。

在为帐户和Sav_acct类创建对象时，您没有维护任何状态。您在这里创建了两个不同的对象。您永远不会在Sav_acct中获得帐户的撤回值，因为两者是不同的对象。此外，您还缺少OOPS中继承的基础知识

由于Sav\u acct是对Account类的扩展，它继承了Account类的所有属性，因此无需创建Account类的对象。相反，创建一个Sav\u acct对象，并使用此对象执行操作；

Account wi = new Account();
wi.withdrawl();             
Sav_acct in = new Sav_acct();
in.interest();

到

Sav_acct wi = new Sav_acct();
wi.withdrawl();
wi.interest();

您需要了解继承在OOPS中是如何工作的。请参阅此处

您可以在需要时多次声明对象。例如：-

System.out.println("Enter your account type: Savings Account or Current Account");
String t = sc.nextLine();
if ("Savings Account".equals(t)) {
    System.out.println("Do you want to deposit or withdraw amount?");
    String d = sc.nextLine();
    if ("deposit".equals(d)) {
        Account de = new Account();        // creating Account object  
        de.deposit();
    }
    else if ("withdraw".equals(d)) {
        Account wi = new Account();   // creating Account object  again
        wi.withdrawl();
        Sav_acct in = new Sav_acct();
        in.interest();
    }
}

在上文中，为什么创建帐户de=新帐户（） 分别用于存款和取款，只需在获取帐户类型名称后声明一个对象，并使用它执行各自的工作。

System.out.println("Enter your account type: Savings Account or Current Account");
String t = sc.nextLine();
if ("Savings Account".equals(t)) {

    Sav_acct acc = new Sav_acct(); //creating sav_acct object here and use 
    
    System.out.println("Do you want to deposit or withdraw amount?");
    String d = sc.nextLine();
    if ("deposit".equals(d)) {
        // Account de = new Account(); no need
        acc.deposit();
    }
    else if ("withdraw".equals(d)) {
        //Account wi = new Account(); no need
        acc.withdrawl();
        //Sav_acct in = new Sav_acct(); no need again
        acc.interest();
    }
}

在main方法中重新设计您的代码，否则大部分事情都很好